This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-168784 filed on Jun. 6, 2000 and Japanese Patent Application No. 2001-118997 filed on Apr. 18, 2001.
1. Field of the Invention
The present invention relates to a motor having a rotatable rotor shaft (rotatable shaft) coupled with a worm shaft via a clutch and also to a manufacturing method of such a motor.
2. Description of Related Art
With reference to FIG. 12, one previously proposed motor used, for example, in a vehicle power window system includes a motor main body 82, an output arrangement 84 and a clutch 85 (FIG. 13). The motor main body 82 has a rotatable shaft 81 that is rotated upon energization of the motor. The output arrangement 84 has a worm shaft 83. The clutch 85 transmits rotation of the rotatable shaft 81 to the worm shaft 83 but prevents transmission of rotation of the worm shaft 83 to the rotatable shaft 81.
As shown in FIG. 13, the clutch 85 includes a driving-side rotator 86, a driven-side rotator 87, a collar 89 and rolling elements 90. The driving-side rotator 86 is secured to a distal end of the rotatable shaft 81 in non-rotatable relationship with respect to the rotatable shaft 81. The driven-side rotator 87 is securely connected to a base end of the worm shaft 83 in non-rotatable relationship with respect to the worm shaft 83. The collar 89 is secured to a gear housing 88 of the output arrangement 84 to surround both the driving-side rotator 86 and the driven-side rotator 87. The rolling elements 90 are positioned between the driven-side rotator 87 and the collar 89.
At an axial center of the driving-side rotator 86, there is provided an annular recess 86a having diametrically opposing flat inner surfaces. Furthermore, at the distal end of the rotatable shaft 81, there is provided an annular protrusion 81a having diametrically opposing flat outer surfaces. When the protrusion 81a is fitted within the recess 86a, the rotatable shaft 81 is secured to the driving-side rotator 86. The inner surfaces of the annular recess 86a are tapered such that a width of the recess 86a increases toward an opening (upper side in FIG. 13) of the recess 86a to facilitate insertion of the protrusion 81a into the recess 86a during assembly.
Protrusions 86b are formed on a worm shaft 83 side of the driving-side rotator 86 at predetermined angular positions at radially outward region of the driving-side rotator 86. Each protrusion 86b axially protrudes toward the worm shaft 83 and extends radially outwardly. A plurality of recesses 87a are formed at predetermined angular positions at a radially outward region of the driven-side rotator 87. A radially inward portion (where a rubber component G is arranged) of each protrusion 86b is received within the corresponding recess 87a of the driven-side rotator 87 in such a manner that a predetermined circumferential space is provided between each protrusion 86b and the corresponding recess 87a. Control surfaces 87b are provided in radially outer surfaces of protruded portions of the driven-side rotator 87 that are formed between the recesses 87a. A radial space between an inner peripheral surface of the collar 89 and each control surface 87b varies in a circumferential direction. Each rolling element 90 is arranged between the corresponding control surface 87b and the inner peripheral surface of the collar 89.
An annular disk portion 89a that extends radially inwardly is formed at one end (upper end in FIG. 13) of the collar 89. An annular cover plate 91 is fitted within the other end (lower end in FIG. 13) of the collar 89. The cover plate 91 and the annular disk portion 89a cooperate to limit axial relative movement of the driving-side rotator 86, the driven-side rotator 87 and the rolling elements 90. More specifically, an inner diameter of the annular disk portion 89a is selected such that the annular disk portion 89a prevents the driving-side rotator 86 to pass through it. Likewise, an inner diameter of the cover plate 91 is selected such that the cover plate 91 prevents the driven-side rotator 87 to pass through it. The other end of the collar 89 (lower end in FIG. 13) is securely fitted within a serrated annular groove 88a formed in the gear housing 88.
The motor having the above-described structure is assembled as follows.
First, with reference to FIG. 14, the driving-side rotator 86, the rolling elements 90 and the driven-side rotator 87 that is previously connected to the worm shaft 83 are inserted inside of the collar 89 from the other end of the collar 89. Then, the cover plate 91 is fitted to prevent these components from falling out of the collar 89. In this way, a clutch-worm shaft unit 92 is assembled. Then, a sensor magnet 93 that constitutes a rotational sensor is secured around a shaft portion of the driving-side rotator 86 which protrudes from the collar 89.
Next, the worm shaft 83 of the clutch-worm shaft unit 92 is received within a worm shaft receiving recess 88b defined within the gear housing 88. More specifically, the worm shaft 83 of the clutch-worm shaft unit 92 is received within a pair of metal bearings 94 retained within the worm shaft receiving recess 88b. During this process, the collar 89 of the clutch-worm shaft unit 92 is clamped by a human hand or chuck claws of a manufacturing device (not shown) to insert the worm shaft 83 of the clutch-worm shaft unit 92 into the worm shaft receiving recess 88b. Then, the other end of the collar 89 is fitted within the serrated annular groove 88a. 
Thereafter, as shown in FIG. 15, a yoke 95 of the motor main body 82 is connected to the gear housing 88 of the output arrangement 84, and the protrusion 81a of the rotatable shaft 81 is fitted within the recess 86a of the driving-side rotator 86 to securely connect the rotatable shaft 81 to the driving-side rotator 86.
In the clutch 85 of the assembled motor, when the motor main body 82 is energized or driven to rotate the rotatable shaft 81 and thereby the driving-side rotator 86, each rolling element 90 is pushed by a radially outward portion of the corresponding protrusion 86b, and a wall surface of each recess 87a of the driven-side rotator 87 is pushed by a radially inward portion of the corresponding protrusion 86b. As a result, the driven-side rotator 87 and the worm shaft 83 are rotated by the driving-side rotator 86.
On the other hand, in a non-actuated state of the motor main body 82, if the driven-side rotator 87 is forcefully rotated along with the worm shaft 83, each rolling element 90 is clamped between the corresponding control surface 87b and the inner peripheral surface of the collar 89 to prevent further rotation of the driven-side rotator 87 (locked state).
While the driven-side rotator 87 is provided as the clutch-worm shaft unit 92 (i.e., while the driven-side rotator 87 is not installed in the gear housing 88), there is a small play between the driven-side rotator 87 and the other clutch components (such as driving-side rotator 86, cover plate 91 or the like), and thereby the driven-side rotator 87 can slightly tilt relative to the collar 89.
Thus, when the collar 89 of the clutch-worm shaft unit 92 is clamped to insert the worm shaft 83 within the metal bearings 94, the worm shaft 83 may swing freely, so that, for example, a worm 83a (tooth) of the worm shaft 83 may contact an inner peripheral surface of the corresponding metal bearing 94 (the contact surface between the worm shaft 83 and the metal bearing 94), resulting in damage to the inner peripheral surface of the metal bearing 94.
The present invention addresses the above described disadvantages. Thus, it is an objective of the present invention to provide a motor that has a rotatable shaft coupled with a worm shaft via a clutch and that allows installation of the worm shaft within a worm shaft receiving recess without inducing damage to the rest of the motor during assembly thereof. It is another objective of the present invention to provide a manufacturing method of such a motor. It is a further objective of the present invention to facilitate the manufacturing of such a motor and also to improve productivity of such a motor.
To achieve the objectives of the present invention, there is provided a method for manufacturing a motor that includes a motor main body, an output arrangement secured to the motor main body, and a clutch arranged between the motor main body and the output arrangement. The motor main body includes a rotatable shaft rotatably supported therein. The output arrangement includes a housing and a worm shaft rotatably supported within the housing. The clutch transmits rotation of the rotatable shaft to the worm shaft and prevents transmission of rotation of the worm shaft to the rotatable shaft. The method includes steps of installing the worm shaft and a driven-side rotator of the clutch in the housing of the output arrangement in such a manner that the worm shaft rotates integrally with the driven-side rotator of the clutch, installing a driving-side rotator of the clutch on the rotatable shaft in such a manner that the driving-side rotator rotates integrally with the rotatable shaft, and connecting the motor main body to the housing of the output arrangement in such a manner that the driving-side rotator is positioned in generally coaxial relationship with respect to the driven-side rotator and is drivingly engageable with the driven-side rotator.
In this method, the worm shaft can be installed in the housing of the output arrangement prior to installing the driven-side rotator of the clutch in the housing of the output arrangement in the step of installing the worm shaft and the driven-side rotator of the clutch. Alternatively, the worm shaft and the driven-side rotator of the clutch can be installed in the housing of the output arrangement as a one-piece member in the step of installing the worm shaft and the driven-side rotator of the clutch.
An annular collar and a rolling element of the clutch can be additionally installed in the housing of the output arrangement upon installing the driven-side rotator in the housing of the output arrangement before connecting the motor main body to the housing of the output arrangement. At the same stage, a support member of the clutch can be additionally installed in the housing of the output arrangement. In this case, the rolling element is first installed in and rotatably supported within the support member prior to being installed in the housing of the output arrangement.
Furthermore, in this method, the collar and the support member can be installed in the housing of the output arrangement while the collar and the support member are correctly positioned with respect to the driven-side rotator using a positioning jig. In this case, the collar and the support member may be correctly positioned with respect to the driven-side rotator in a rotational direction of the driven-side rotator by engaging the positioning jig with a positioning portion of the collar, a positioning portion of the support member and a positioning portion of the driven-side rotator, respectively.
Also, operation of the clutch can be tested just before the step of connecting the motor main body to the housing of the output arrangement. The operation of the clutch can be tested with an operation testing jig that is engageable with a rotational drive coupling portion of the driven-side rotator to rotate the driven-side rotator. The test may be conducted by inserting an operation testing jig along a installing direction of the driving-side rotator, engaging the operation testing jig with the rotational drive coupling portion, and directly rotating the driven-side rotator by the operation testing jig.
Furthermore, to achieve the objectives of the invention, there is provided a motor including a motor main body, an output arrangement secured to the motor main body, and a clutch arranged between the motor main body and the output arrangement. The motor main body includes a rotatable shaft rotatably supported therein. The output arrangement includes a housing and a worm shaft rotatably supported within the housing. The clutch transmits rotation of the rotatable shaft to the worm shaft and prevents transmission of rotation of the worm shaft to the rotatable shaft. The clutch includes a driven-side rotator, a driving-side rotator, an annular collar and a rolling element. The driven-side rotator rotates integrally with the worm shaft. The driving-side rotator is positioned in generally coaxial relationship with respect to the driven-side rotator and rotates integrally with the rotatable shaft. The driving-side rotator is drivingly engageable with the driven-side rotator. The annular collar is received in the housing of the output arrangement in non-rotatable relationship with respect to the housing and surrounds both the driving-side rotator and the driven-side rotator. The driven-side rotator includes a control surface facing an inner peripheral surface of the collar. The control surface is spaced from the inner peripheral surface of the collar for a distance that varies along a circumferential direction of the collar. A smallest inner diameter of the collar is larger than a largest outer diameter of the driving-side rotator, so that the driving-side rotator is axially detachably engageable with the driven-side rotator through the collar. The rolling element is positioned between the control surface of the driven-side rotator and the inner peripheral surface of the collar. The rolling element rotates integrally with the driven-side rotator when the driving-side rotator is rotated upon energization of the motor. The rolling element is clamped between the control surface of the driven-side rotator and the inner peripheral surface of the collar to prevent rotation of the driven-side rotator when the driven-side rotator is rotated by an external force.
The worm shaft can be formed separately from the driven-side rotator. Alternatively, the worm shaft and the driven-side rotator can be formed together as a one-piece member.
Furthermore, the clutch can further includes a support member for rotatably supporting the rolling element. The support member is rotatably supported within the housing of the output arrangement between the driven-side rotator and the collar.
Also, the driven-side rotator can include a rotational drive coupling portion for engaging with an operation testing jig for testing operation of the clutch.
Moreover, each one of the collar, the support member and the driven-side rotator can include a positioning portion for engaging with a positioning jig.